The present invention relates to an embedded antenna for a mobile terminal, particularly to an embedded antenna for a terminal of a GSM/DCS dual frequency mobile communication system.
Along with the rapid development and widespread application of mobile communication technology, mobile telephones tend to be much more compact, to support multi-mode (to be compatible to GSM900/DCS1800, PCS, IS-95 and future 3G systems), and to be of higher performance.
For manufacturers of the mobile terminals, the radio frequency (RF) part, the base band part and the digital signal processing (DSP) part of a mobile terminal have so far been implemented at a high level integration, which strongly facilitate the reduction of size and cost of mobile terminals. However, the antenna part as well as its"" feed part of a mobile terminal, have progressed slowly for their performance and size having been limited by the terminal structure, fixed positions of electronic component, and characteristics of material of the terminal housing. Thus the integration level of the antenna of the mobile terminal is still relatively low and the cost is still relatively high, thereby restricting the further development of the mobile terminal. Due to the combination of the mobile communication and computer networks the problem will be more serious in the future mobile terminal supporting multi-mode.
On the other hand, as people increasingly realize that the mobile terminal""s electromagnetic radiation may impose the damage on a human body, users are intensively demanding a mobile terminal with a low electromagnetic radiation without degrading its existing performance. With respect to external antenna technologies widely used in the mobile terminals, it is typical to adopt an antenna or its combination that is symmetric in structure and radiating directions. Consequently, it is impossible to meet the above-mentioned requirements of the users.
Embedded antennas have been developed under this circumstance. Using the embedded antennas, a mobile terminal may have a more flexibility in shape design and smaller size, a lower signal absorption ratio (SAR), and a higher peak gain, and among other things, an embedded antenna can be used to implement an antenna array with a relatively small size. It can be envisioned that the embedded antenna represents a future development direction of mobile terminal antennas.
However, all the existing planar embedded antennas have been designed within a two-dimensional plane. Since such designs have only two dimensions for extension, there are some disadvantages as follows:
1. the antenna is too large to be applicable to the minimized mobile terminals (such as pocket handsets) whose sizes are greatly restricted;
2. the embedded antenna needs a support or be attached to a housing for its installation, thereby causing increasing of production cost and degrading of reliability and maintainability;
3. the electrical characteristics are relatively poor, for example, the in-band Voltage Standing Wave Ratio (VSWR) is too high, which reduces the efficiency of the antenna and increase the power reflection of the handset.
In order to overcome the disadvantages of the prior art as described above, it is an object of the invention to provide an embedded antenna for a mobile terminal with a three-dimensional structure.
In one aspect of the invention, there provides an embedded antenna for a mobile terminal, comprising a conductor unit, including a print-circuit-board (PCB), and having a metal-layer-stripped region formed on the top of the conductor unit; an antenna unit, including another PCB, being vertically connected to the metal-layer-stripped region on top of the conductor unit, and having a ground pin and a feed pin to be connected to circuits within the mobile terminal; a parasitic unit, with one side being attached to the antenna unit, and another side being apart from and in parallel to the antenna unit.
Further more, the antenna unit may be substantially rectangular, and have a first long edge connected to the conductor unit, a second long edge opposite to the first one and being apart from the conductor unit, and a first and a second short edge opposite to each other; wherein the antenna unit has a C-shaped etched region in the middle of a second surface, where the opening of the C shape is directed to the second short edge, the etched region begins from the middle of second long edge of the antenna unit, extends towards the first long edge and then towards the first short edge, extends once again towards the first long edge and then towards the second short edge, and finally protrudes towards the second long edge at its rear end.
According to another aspect of the invention, there provides a mobile terminal having an antenna as described above, wherein said mobile terminal comprises a grounding board to be used as a conductor unit.